SYNOPSES AND DESCRIPTIONS. 15 
about one third as large as the prefrontals. Rostral subtriangular, broader 
than high. Nasal divided, nostril mainly in anterior portion. Loreal 
small. Preocular narrow, high. Postoculars two (sometimes one), small, 
lower resting on the fifth labial. Labials eight, fourth and fifth in orbit, 
sixth and seventh larger. Infralabials nine, sixth larger. Submentals 
two pairs, anterior larger, posterior separated by small scales. Scales 
lozenge-shaped, smooth, in 17 rows, medial and outer broader. Ventrals 
244 (228—259). Anal bifid. Subcaudals 134 pairs (134—174.) 
Light greyish-brown, scales more or less punctulate with brown. Ante- 
riorly with dark-edged transverse blotches of brown; posteriorly these 
become smaller, do not descend on the flank, and are very irregular and 
broken. Hinder portion of body with spots irregularly distributed on the 
lower portions of the flanks. Specimen described from Acapulco, Mex. 
Total length 33 inches; tail 10 in. Hab. Mexico to Brazil. 
Dipsas LEUCOMELAS. 
HIMANTODES LEUCOMELAS Cope, 1861, Proc. Ac. N. Se. Phil., 296. 
Lateral borders of frontal nearly parallel, longer than the anterior. 
Loreal higher than long. Two preoculars, not in contact with the frontal. 
Infralabials ten, sixth largest. Seales smooth, in 17 rows, vertebral larger, 
broader than long. ‘Total length about three and one half times that of 
the tail. 
Greyish, crossed by about twenty-nine black bands, which encroach on 
the ends of the ventrals. About eighteen spots on the tail. Spotted or 
dotted with black on the belly. A pair of black spots from the supracil- 
iaries over the occipitals to the neck. A band of black across the pre- 
frontals. Scale pores single. (Unknown to me.) Vera Cruz. 
SrBon. 
Fitzinger, 1826. 
Moderately long, slightly compressed, tapering to head and tip of tail; 
head distinct, large, broad, depressed, with broad muzzle; tail moderate. 
Eye medium, pupil oblong, erect. Posterior maxillary teeth longer, 
grooved. Head-shields regular. Nasal in two parts, nostril between. 
One or more loreals. Oculars 1 to 3—2 to 3, sometimes with suboculars. 
23 rows, dorsal not larger. Anal and 
Seales smooth, imbricate, in 19 
subeaudals divided, Hab. Texas and Mexico to Brazil, 
